1. Field of the Invention
The present invention relates to an absorbent article suitable for absorbing menstrual blood and so on discharged from a woman's genital organ, more particularly, relates to an elongated absorbent article intended to cover the wearer's body from a vaginal opening to buttocks.
2. Description of the Related Art
Absorbent articles intended to absorb menstrual blood discharged from a woman's genital organ are typically constructed to include a liquid absorbent layer, a liquid-permeable topsheet covering the skin surface of the liquid absorbent layer, and a liquid-impermeable backsheet covering the garment surface of the liquid absorbent layer, and generally, they are worn with the backsheet adhered to an inner side of a groin piece of an undergarment through a pressure-sensitive adhesive layer.
In such an absorbent article, the function of certainly collecting menstrual blood applied to the skin surface is required so as to prevent lateral leakage of liquid and rearward leakage of liquid from the absorbent article.
Particularly in an absorbent article that is intended to be worn by a woman during menstruation while sleeping, required is not only prevention of lateral leakage of menstrual blood from the absorbent article but certain absorption of menstrual blood trying to flow along the wearer's body toward the anus and the cleft of the buttocks or trying to flow along the skin surface of the absorbent article rearwardly without causing any leakage. Accordingly, such an absorbent article for nighttime use is elongated more than absorbent articles for daytime use so that its skin surface can cover a large area from a mons pubis which is anterior to the vaginal opening to the buttocks which is posterior to the anus.
Japanese Unexamined Patent Publication No. 2001-95842 (Patent Publication 1) discloses an elongated sanitary napkin which is intended for nighttime use. In this sanitary napkin, the skin surface is provided with a circular emboss and the region surrounded by the circular emboss is a high-center portion, wherein the high-center portion is elongated longitudinally of the sanitary napkin. At a position between front and rear regions, the lateral separation distance between opposing portions of the circular emboss is increased to provide swelling embosses. On its skin surface, furthermore, longitudinally extending gathered cuffs are provided at both sides thereof, along with elastically extensible members for raising the gathered cuffs.
The invention disclosed in Patent Publication 1 aims at swelling a portion having the swelling embosses toward the wearer's body by making use of a longitudinal shrinkage force of the elastically extensible members exerted on the sanitary napkin so that the portion having the swelling embosses may fit on the wearer's body.
On the other hand, Japanese Unexamined Patent Publication No. 2001-129018 (Patent Publication 2) discloses an absorbent article whose skin surface is provided with leakage preventing grooves which are mutually connected to surround an elongated liquid receiving region, wherein the mutually connected leakage preventing grooves are doubled in a rear portion. This invention aims at preventing rearward leakage of menstrual blood from the absorbent article by doubling the mutually connected leakage preventing grooves.
In the invention disclosed in Patent Publication 1, however, stiffness of the sanitary napkin in the portion having the swelling embosses differs little from that in portions forward and rearward thereof. Therefore, when the longitudinal shrinkage force of the elastically extensible members is exerted, the portion having the swelling embosses tends to be folded on its laterally extending fold line, so that the portion having the swelling embosses is easily folded toward the wearer's body while swelling in a direction perpendicular to the cleft of the buttocks. That is, because the portion having the swelling embosses is folded while being widened in a direction perpendicular to the direction of recesses anterior and posterior to the perineum, it is difficult for the skin surface of the sanitary napkin to come into close contact with the perineum and portions anterior and posterior thereto without fail.
In the sanitary napkin disclosed in Patent Publication 1, moreover, the skin surface is sometimes curved away from the wearer's body due to the longitudinal elastic shrinkage force of the elastically extensible members. When thus deformed, the portion having the swelling embosses is easily separated from the wearer's body to leave a space between the skin surface and the perineum and portions anterior and posterior thereto.
Furthermore, since the sanitary napkin disclosed in Patent Publication 1 is provided with almost constant stiffness over the region from the intermediate portion having the swelling embosses to the rear portion, the whole body tends to deform freely over the region from the intermediate portion to the rear portion. Therefore, when movement of the buttocks exerts an external force on the intermediate and rear portions, the sanitary napkin is twisted or wrinkled to increase the possibility of leaving a space between the wearer's body and the skin surface.
On the other hand, since the mutually connected leakage preventing grooves disclosed in Patent Publication 2 are doubled in the rear portion, stiffness is increased only in the rear portion with the double portion of the mutually connected leakage preventing grooves. Therefore, the absorbent article is easily folded at the boundary between the single portion and the double portion of the mutually connected leakage preventing grooves and separated from the wearer's body at this portion, i.e., portion which is intended to face the woman's perineum. This results in that menstrual blood tends to flow rearwardly along the wearer's body, so that the cause of rearward liquid leakage cannot be basically eliminated.